1. Technical Field
The present invention relates to a liquid ejection apparatus.
2. Related Art
An ink jet printer allows an ink filled in an ejection unit to be ejected and forms an image on a recording medium by allowing a piezoelectric element provided in the ejection unit to be driven by a driving signal.
However, when the ink in the ejection unit is thickened, ejection abnormality occurs and the image quality of the image to be printed is degraded in some cases. Further, in a case where the ink in the ejection unit includes bubbles or paper dust is adhered to the vicinity of a nozzle of the ejection unit, ejection abnormality occurs and the image quality of the image to be printed is degraded in some cases. Accordingly, it is preferable to inspect an ejection state of the ink in the ejection unit for realizing high grade printing.
JP-A-2013-028183 discloses a technique of detecting residual vibration generated by allowing the piezoelectric element to be driven by the driving signal and inspecting the ejection state of the ink in the ejection unit based on detection results.
The inspection of the ejection state of the ink in the ejection unit is performed using a residual vibration waveform when the piezoelectric element is driven. It is possible to specify the cycle of the residual vibration by measuring the cycle of a comparison signal obtained by comparing the residual vibration waveform with a predetermined threshold potential.
However, in regard to information of the residual vibration waveform in an amplitude direction, it is necessary to perform AD conversion on the residual vibration waveform, but there is a problem in that the configuration of an AD converter is complicated.